How does Connor discover that he's going to be unwound?
You can find the answer to this question in chapter one. This chapter introduces readers to Connor. When the chapter begins, Connor is out with his girlfriend, Ariana. She and Connor are talking about "kicking AWOL" together. Connor knows that this is a huge commitment on Ariana's part. Her parents are not having her unwound. She is only thinking about going AWOL because she wants to be with Connor. Connor then takes her home, and he heads home himself. He greets his father, and then the novel goes into a brief flashback to explain how Connor knows that he is going to be unwound.
Three weeks earlier, Connor was looking for a stapler in his dad's office. While searching, Connor found three plane tickets to the Bahamas. His name was not on any of the tickets. Connor thought that was weird, so he kept searching through the house. Eventually, Connor found the Unwind order. It had already been signed, and the white triplicate copy was already off to the authorities. Connor was guaranteed to be an Unwind at that point.
So Connor went looking a little deeper when his parents were out, and he found it. The Unwind order. It had been signed in old-fashioned triplicate. The white copy was already gone—off with the authorities. The yellow copy would accompany Connor to his end, and the pink would stay with his parents, as evidence of what they'd done.